It reads like (yet another) DNS problem. (There have been loads of similar questions here on AB recently. I've even had to change my own DNS settings to overcome a similar problem).
When you type in a URL, your request is routed via your ISP's domain name server (DNS). This changes the alphanumeric address (e.g. www.theanswerbank.co.uk) to the 'true' numeric address (called a 'logical address') of the server you're trying to access. (e.g. AB's logical address is 91.186.31.12).
Sometimes your PC can fail to make a proper connection to your ISP's domain name server, which results in a 'bottleneck' in the link between your PC and the site you're trying to access.
You need to go into your PC's internet connection settings. Unfortunately, I'm using dial-up with Windows ME, so I can't tell you exactly what you need to do (since you're probably using broadband with XP or Vista) but you'll probably find that you need to right-click on the icon for the connection and select 'Properties'. Then you need to look for 'TCP/IP Settings'. (It's probably under 'Networking'). Click to place a dot alongside 'Specify name server addresses'. Alongside 'Primary DNS' enter these numbers:
208.67.222.222.
Alongside 'Secondary DNS' enter these numbers:
208.67.220.220
Leave the other lines unchanged. Click 'OK' twice.
When you next connect to the internet, you're PC should now be able to make a proper DNS connection and everything should be OK.
Chris
PS: The domain name server I've given you the logical address for is a public DNS, which can be used from any ISP. If you'd rather stick with your ISP's DNS, the relevant addresses can be found on your ISP's website.